ABSTRACT- In this paper we study the Black Death persecutions (1347-1352) against Jews in order to shed light on the factors determining when a minority group will face persecution. We develop a theoretical framework which predicts that negative shocks increase the likelihood that minorities are scapegoated and persecuted. By contrast, as the shocks become more severe, persecution probability may actually decrease if there are economic complementarities between the majority and minority groups. We compile city-level data on Black Death mortality and Jewish persecution. At an aggregate level we find that scapegoating led to an increase in the baseline probability of a persecution. However, at the city-level, locations which experienced higher plague mortality rates were less likely to engage in persecutions. Furthermore, persecutions were more likely in cities with a history of antisemitism (consistent with scapegoating) and less likely in cities where Jews played an important economic role (consistent with inter-group complementarities).

Both history and the current world provide several examples of ethnic and religious minorities becoming the target of persecutions by the majority. Especially after the Holocaust, a growing number of scholars from different fields have inquired into the causes of these persecutions. In particular, the question is whether the chance of persecution against minorities is directly related to negative shocks such as harvest failures, economic depressions or plague. This paper by Jedwab, Johnson and Koyama addresses this question by looking at the persecutions against Jews during the Black Death (1347-1352) in Europe. The authors adopt a theoretical framework in which the negative shock represented by the Black Death has two possible effects on the probability of persecutions: on the one hand, the scapegoating effect leads to attributing the responsibility of the plague to the Jews, decreasing the preference for diversity in society and therefore leading to persecutions. On the other hand, if the minority represents some value to the majority (for instance because of money lending or because of high-skill jobs in which they cannot be easily replaced), the incentive to persecute decreases, with the complementarity effect prevailing. The two effects compete and the decision to persecute Jewish communities depends on the comparison between the utility that the majority derives from persecution and the economic benefit that the minority provides if left untouched.

The authors compile a dataset for 124 locations containing plague mortality rates from Christakos et al. (2005) and information on Jewish persecutions mainly from Encyclopedia Judaica. The aim is to test the effect of mortality caused by the Black Death on the probability of persecution of the local Jewish community. To assure the reader on the soundness of their identification strategy, the authors collect an impressive number of geographical and institutional controls to capture the effect of several other elements that could trigger persecutions. The paper of course cannot take into account all potential sources of bias but the authors thoughtfully address several potential problems using anecdotal and scientific evidence, proposing some convincing arguments to defend their choices. For instance, they spell out in detail the characteristics of the contagion proving that its pattern was largely determined by chance. The virulence of the plague was also unaffected by human behavior (by both Jews and non-Jews), ruling out the possibility of some causality running from the presence of Jews to the intensity of the plague. The instruments for mortality are also quite convincing: the two IV proposed are distance from Messina (a Sicilian port city where the first contagion was recorded) and month of the first infection. If it is true that the geographical origin and pattern of propagation of the Black Death were random, the instruments appear exogenous.

Figure 1: Pogrom of Strasbourg (1349) by Emile Schweitzer

Unsurprisingly, the authors find that the period 1347-1352 has indeed seen an unpreceded (and unrepeated until WWII) wave of persecutions against Jewish communities in Europe (Figure 2).

Figure 2: Total Number of Jewish Persecutions in 1100-1600.

What is far more surprising is that there is indeed a general increase in the baseline level (basically, on the intercept) but this effect does not grow stronger as mortality rates are higher. In the model, the constant is 0.831 which indicates a high risk of being persecuted on average but the effect of mortality of the persecution probability is negative and quite substantial (minus 0.34 standard deviations for one standard deviation increases in mortality). The shock appears to have a counter-veiling effect, as cities with the highest mortality were less likely to persecute Jews. In essence, in cities where Jews have a strong economic role, the complementarity effect prevailed. The take home message is therefore that persecutions have a general ideological origin but economic incentives can at least reduce violence against minorities.

This paper is nested into a very large literature on the origins and determinants of persecutions. On the Jewish case, a recent paper by Voigtländer and Voth (2012) has shown that the location of the persecutions during the Black Death in Germany is a strong predictor of the location of episodes of violence against Jews in the 1920s. This paper fills a gap by looking at the determinants of the medieval persecutions in first place. This work is also well connected to the body of research looking at the economic aspects of Jewish history, to which Botticini and Eckstein (2012) provided a seminal contribution. On a more general note, this paper represents a call for the inclusion of a microeconomic perspective when studying how persecutions of minorities arise.